JPS6050368B2 - photocurable hydrosol - Google Patents

Description

[Detailed description of the invention] This invention relates to photocurable hydrosols.

More specifically, the polymer particles are stably dispersed in water,
The present invention also relates to a photocurable hydrosol that forms a film with good water resistance and adhesion. Recently, energy saving,
From the viewpoint of labor saving and environmental conservation, the development of solvent-free resins that dry and harden by irradiation with active energy rays such as infrared rays, ultraviolet rays, or ionizing radiation is active, and they are used in printing inks, printing plate materials, photoresists, paints, and adhesives. It is being put into practical use in a wide range of fields, including pharmaceuticals.

Common solvent-free resins include acryloyl group, vinyl group, acrylamide, -,
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i-'-■譬一■go',-! ■2-1 Nmm, (1■■(1-) A compound that is mainly composed of a radically polymerizable compound that is a combination of prepolymers, oligomers, or monomers, and contains photosensitizers, pigments, dyes, etc. as necessary. However, the films obtained by curing these solvent-free resin compositions by irradiation with active energy rays have a fast curing reaction rate, which makes it difficult to relieve internal stress due to curing shrinkage, and they generally have poor adhesion. There were other drawbacks.

In order to improve the flexibility of the film, it is necessary to improve the flexibility of the film, by adding a high molecular weight polymer to the resin composition, or by adding a polymer or oligomer containing a radically polymerizable unsaturated group. Possible methods include making the skeleton flexible and increasing the molecular weight, but such methods result in a resin composition that is extremely viscous, making it difficult to apply it uniformly to the adherend. A new drawback arises.

Therefore, as a result of repeated research aimed at solving the above-mentioned drawbacks, the inventors of the present invention found that a hydrosol in which a specific pre-curable acrylic polymer and a photosensitizer were stably dispersed in water was developed. We discovered that the above drawbacks could be solved,
This invention has been made. That is, this invention consists of 98 to 1% by weight of the main monomer mainly consisting of 5-acrylic acid ester or 5-methacrylic acid ester, and 2 copolymerizable unsaturated monomers having an acidic group consisting of a carboxyl group or a sulfonic group. A compound having a (meth)acryloyl group is added to an acrylic copolymer consisting of ~2% by volume and 0 to 7% by volume of a copolymerizable unsaturated monomer having active hydrogen other than the above acidic group. This invention relates to a photocurable hydrosol in which a photocurable copolymer and a photosensitizer are stably dispersed in water.

The cured film obtained using the photocurable hydrosol of this invention has good adhesion and water resistance, and even though this composition contains an organic solvent, it has a low viscosity and has excellent coating workability. It is something that

The acrylic copolymer used in this invention contains 98 to 1% by weight, preferably 95 to 45% by weight of the main monomer mainly consisting of acrylic ester or methacrylic ester, and an acidic copolymer consisting of carboxyl or sulfonic groups. 2 to 2% by weight of copolymerizable unsaturated monomers having groups, preferably 5 to 15% by weight in the case of unsaturated carboxylic acids, 3 to 10% by weight in the case of unsaturated sulfonic acids, and other than the above acidic groups Copolymerizable unsaturated monomer having active hydrogen of 0 to 7% by weight
, preferably by polymerizing a monomer composition consisting of 0 to 40% by weight by any known method such as bulk polymerization, solution polymerization, emulsion polymerization, or bar polymerization. .

As the main monomer, the alkyl group has 1 to 15 carbon atoms.
In particular, 3 to 10 acrylic esters or methacrylic esters are preferably used in an amount of 70 to 100% by weight based on the main monomer, and other materials such as vinyl ether, tel, vinyl ester, acrylonitrile, acrylamide, styrene, vinyl chloride, etc. of unsaturated monomers in the amount of 0 to 3% of the main monomers
It is best to use it so that

The copolymerizable unsaturated monomer 3 having an acidic group is an unsaturated carboxylic acid having a carboxyl group as an acidic group, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, or fumaric acid. , ma', t are styrene sulfonic acid, allyl sulfonic acid, sulfopropyl acrylate, 2-acryloyloxynaphthalene-2-sulfonic acid, 2-methacryloyloxynaphthalene-2-
Unsaturated sulfonic acids having a sulfonic group as an acidic group are used, such as sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and 2-acryloyloxybenzenesulfonic acid, and one or more of these are used.

The amount of the above unsaturated monomer used is 2 to 2% of the total monomers.
If the amount used is less than 2% by weight or exceeds 2% by volume, good results will not be obtained in hydrosolization.

Copolymerizable unsaturated monomers having active hydrogen other than the above acidic groups include N-methylolacrylamide, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, allyl alcohol, polyethylene glycol, and (meth)acrylic acid. Hydroxyl group-containing monomers such as ethylene glycol or monovinyl ether of polyethylene glycol, monovinyl ether of propylene glycol or polypropylene glycol, aminoethyl (meth)acrylate, N-methylaminoethyl (meth)acrylate, Primary to secondary such as N-ethylaminoethyl (meth)acrylate
Examples include amino group-containing monomers of the same class.

After polymerizing by any polymerization method using the above monomer,
In the emulsion polymerization method, water and unreacted substances are removed by coagulating and separating by salting out, and in the bar polymerization method, water and unreacted substances are separated by filtering the particulate copolymer. .

In addition, in the emulsion polymerization method and the crowbar polymerization method, the emulsifier used during polymerization partially adheres to the surface of the polymer particles, but this emulsifier is removed during the above removal operation, and if necessary, it can be removed by washing. Bye. Copolymers thus obtained by emulsion polymerization, crowbar polymerization, or bulk polymerization may be prepared after adding a small amount of inert solvent, if necessary, or by removing the solvent in the case of solution polymerization. Next stage (meta)
Used for reactions with compounds having an acryloyl group.

As the compound having a (meth)acryloyl group used in this invention, 2-(1-aziridinyl)ethyl (
Aziridinyl group-containing monomers such as meth)acrylate, 2-(1-aziridinyl)butyl (meth)acrylate, and 2-(1-aziridinyl)propyl (meth)acrylate; epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate; or a monomer having a (meth)acryloyl group among the copolymerizable unsaturated monomers having an acidic group or other active hydrogen, and tolylene-24-diisocyanate, tolylene-2,6-diisocyanate, diphenylmethane-4・4-diisocyanate, naphthylene-1●5-diisocyanate,
Isocyanate group-containing compound such as a reaction product of polyhydric alcohol such as polyethylene glycol or polypropylene glycol and tolylene diisocyanate, 1.*
: Choichi (4-methyl-m-phenylene)-bis-3.3
-aziridinyl urea, 11"-(hexamethylene)-bis-3,3-aziridinyl urea, 1-(methylene-di-P-phenylene)-bis-3,3-aziridinyl urea, ethylene bis(2-aziridinylpropionate) )
Examples include aziridinyl group-containing compounds, such as aziridinyl group-containing compounds, and 1:1 (molar ratio) adducts with bisphenol A-type epoxy group-containing compounds represented by the following general formula.

(In the formula, n is O to 12) A photocurable copolymer can be obtained by adding a compound having these (meth)acryloyl groups to the acrylic copolymer.

The amount of the compound having a (meth)acryloyl group to be added may be appropriately determined depending on the content of the copolymerizable unsaturated monomer having an acidic group or other active hydrogen in the acrylic copolymer. When a monomer having an active hydrogen other than an acidic group is not used, the amount of addition is such that the acidic group remains in the copolymer even after the addition reaction. The photosensitizer to be mixed with the photocurable copolymer thus obtained is not particularly limited as long as it promotes the photopolymerization reaction of the photocurable copolymer, but for example, Benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, α-methylbenzoin, anthraquinones such as 1-chloroanthraquinone and 2-chloroanthraquinone, benzophenone, p-chlorobenzophenone, p-
Examples include benzophenones such as dimethylaminobenzophenone, sulfur-containing compounds such as diphenyl disulfide and tetramethylthiuram disulfide, and such photosensitizers are usually combined with the photocurable copolymer. It is added in an amount of 0.05 to 20% by weight, preferably 0.5 to 1% by weight based on the total amount.

In this invention, next, if necessary, the organic solvent and unreacted substances are removed from the mixture of the photocurable copolymer and the photosensitizer by means such as distillation, and then, if necessary, hydrosolization is performed. Methanol, ethanol, n
- After adding an alcoholic water-soluble solvent such as propanol, isopropyl alcohol, Sec-butanol,
Neutralize by adding alkali and water while stirring.

The treatment temperature at this time is kept at a constant temperature depending on the type and properties of the copolymer, but is generally 40 to 95°C.
Examples of the alkali or alkaline aqueous solution used for neutralization include ammonia, aqueous ammonia, caustic soda, and caustic alkali aqueous solutions such as caustic potash. Generally, it may be used in an amount of about 1,150 to 2 equivalents relative to acidic groups such as carboxyl groups and sulfone groups in the copolymer. After this neutralization treatment, if water is gradually added while stirring and mixing well, a so-called phase inversion phenomenon will occur at regular intervals, and the water will form a continuous layer, in which it will coexist. An O/W type dispersion in which polymer particles are dispersed is produced.

After forming this dispersion, gradually add the required amount of water,
The photocurable hydrosol of the present invention can be obtained by adjusting the viscosity and solid content concentration of the dispersion. The viscosity is generally 30 to 1,000 poise at 25°C, and the solids concentration is usually 10 to 6% by weight. Appropriate amounts of other compounding agents can be added to the hydrosol depending on the purpose.

The timing of addition may be before or after hydrosolization. Examples of compounding agents include photocurable monomers or oligomers such as ethylene glycol di(meth)acrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, acrylic-modified polyester, coloring or decoration, etc. for the purpose of increasing film hardening. For example, pigments such as zinc white, yellow lead, and red iron oxide, dyes such as toluidine red, phthalocyanine blue, and phthalocyanine green, and other metal powders, glass beads, glass powder, and glass flakes may be used.

In the photocurable hydrosol configured in this way, the average particle diameter of the copolymer as the dispersed particles is 0.01 to 0.1 μm, and the copolymer particles are uniformly and stably dispersed in water. It is a hydrosol, and by casting it onto a carrier, heating and drying it, and then curing it by irradiating it with light, a cured film with good water resistance and adhesion can be obtained.

The heating drying described above may be performed at 80 to 150°C for about 5 minutes, and the light irradiation is performed for 3 seconds or more, preferably 3 seconds using a light source such as a high-pressure mercury lamp, ultra-high pressure mercury lamp, metal halide lamp, carbon arc lamp, or xenon lamp. Do the above.

Note that this photocurable hydrosol can also be cured by electron beam irradiation, and in this case, it is not necessary to intentionally add a photosensitizer.

Examples of this invention will be described below.

In addition, in the following, parts mean parts by weight. Example 1 Ethyl acrylate (4)
Part octyl acrylate (To) Part acrylic acid 1 Part acrylic acid 2
-Hydroxyethyl w-benzoyl monoperoxide
0.15 parts benzene
2 (4) parts of the above raw material composition was charged into a 1E flask and reacted at 65°C for 4 hours with stirring under a nitrogen stream to obtain a weight average molecular weight of 3.5 x 1I (by GPC).
An acrylic copolymer was synthesized.

Next, 0.1 part of dibutyltin dilaurate was added to the above reaction solution containing this copolymer while stirring at 40°C, and then added with 2-hydroxyethyl acrylate 24-tolylene diisocyanate in a molar ratio of 1:1. 25 parts of the mixture was added over 1 hour, and the mixture was further stirred at 60°C for 3 hours.

Subsequently, 3 parts of benzoin isopropyl ether were added, and then benzene and unreacted monomers were distilled off under reduced pressure. To 125 parts of the thus obtained mixture of the photocurable copolymer and photosensitizer were added 2 parts of isopropyl alcohol, the temperature was raised to 60°C, and 1 part of an aqueous solution of caustic soda at 1% volume was added. After neutralization, 250 parts of water was gradually added to obtain a translucent photocurable hydrosol.

This hydrosol has a viscosity of 270 poise and a solid concentration of 2
The heel volume was %.

Example 2 Methacrylic methyl, Vinyl acetate, Methacrylic acid
3CyIf) 10 parts of the above monomer mixture, 20 parts of Sec-butanol, and 0.15 parts of benzoyl peroxide were placed in a 1' flask, heated to 80°C with stirring under a nitrogen stream, and then the remaining monomer mixture was heated for about 2 hours. The mixture was added dropwise and heated and stirred at 65° C. for another hour to synthesize an acrylic copolymer having a weight average molecular weight of 2.0×1σ (according to GPC).

Next, 35 parts of 2-(1-aziridinyl)ethyl acrylate was added to the above reaction solution containing this copolymer while stirring at 400C for 1 hour, and after further reaction at 60C for 3 hours, benzyl dimethyl ketal 3 A mixture of a photocurable polymer and a photosensitizer was obtained.

Next, 135 parts of this mixture was neutralized by adding 1 volume% ammonia aqueous solution, and 270 parts of water was gradually added.
A translucent photocurable hydrosol was obtained.

The hydrosol thus obtained had a viscosity (at 25° C.) of 320 poise and a solid content concentration of 2% by weight. Example 3 Butyl acrylate Marked part Methyl methacrylate 2 parts Phosphoethyl methacrylate 13 parts Methacrylic acid
7 parts 2-mercaptoethanol 0
．． 1 part Azobisisobutyronitrile 0.1 part 1
' In a flask, add 0.1 part of polyvinyl alcohol to 2 parts of water.
(9) parts, the above monomer composition was added, polymerization was carried out for 4 hours under a nitrogen stream, and the weight average molecular weight was 3.0 x 1σ (
According to GPC), a burl-shaped copolymer was obtained.

Next, only the burl-shaped copolymer was passed through the mouth, washed, and dried, and then 8 parts of glycidine methacrylate was added to 1 (1) part of this copolymer, and the 3 powders were thoroughly stirred at 40°C.゜C
After stirring for 2 hours, 2 parts of benzyl dimethyl ketal was added to obtain a mixture of a photocurable polymer and a photosensitizer. Next, 108 parts of this mixture was added with 2% w weight % ammonia aqueous solution.
was added for neutralization, and 250 parts of water was gradually added to obtain a translucent photocurable hydrosol.

The hydrosol thus obtained had a viscosity (25°C) of 250 poise and a solids concentration of 28% by weight. The photocurable hydrosols obtained in Examples 1 to 3 above were applied onto a stainless steel plate to a dry thickness of 10 pm, and dried by heating at 100°C for 3 minutes.

Next, this composition was irradiated with light for 5 seconds from a height of 10 cm using a high-pressure mercury lamp (80 W/(:RrL)) to form a cured film.
The results of hardness, adhesion, flexibility, and water resistance are shown in the table below.

The above test was conducted as follows.

Curing property: The stickiness was examined by finger touch and evaluated on a 3-level scale.

Those with no stickiness were rated as having good curability (0), those with some stickiness were rated as having slightly poor curability (Δ), and those with a lot of stickiness were rated as poor curability (×). Hardness: Depends on enbit hardening.

Adhesion: 1? on 10Crf1 x 10cm cured film. Cuts in the shape of a grid of width were made, cellophane tape was pasted on the film, and when the tape was peeled off, the percentage of the number of cuts that were not peeled off was determined.

Flexibility: Using a bending tester (JIS-K-5400), the state of the film was evaluated in three stages at a bending radius of 2T1$t and a bending angle of 1800, with the film surface facing outward.

Those with no change in the film were rated as having good flexibility (○), those with slight cracks were rated as having slightly poor flexibility (Δ), and those with cracking and peeling were rated as having poor flexibility (x). Water resistance: After being immersed in water at 20'C for 72 hours, the degree of whitening and peeling was evaluated in three grades.

Claims (1)

[Claims] 1 98 to 10% by weight of a main monomer mainly composed of acrylic ester or methacrylic ester, 2 to 20% by weight of a copolymerizable unsaturated monomer having an acidic group consisting of a carboxyl group or a sulfonic group, and the above acidic group. A photocurable copolymer and photosensitization made by adding a compound having a (meth)acryloyl group to an acrylic copolymer consisting of 0 to 70% by weight of a copolymerizable unsaturated monomer having an active hydrogen other than A photocurable hydrosol made by stably dispersing an agent in water.